nitrophenols and pyridine

In the present study, a series of substituted 1,3,4-thiadiazole derivatives 4(a-o), 5(a-m) and 6(a-j) were synthesized and characterized by IR,

Topics: Animals; Antitubercular Agents; Chlorocebus aethiops; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Nitrophenols; Pyridines; Structure-Activity Relationship; Thiadiazoles; Tuberculosis, Multidrug-Resistant; Vero Cells

Water-based Zn(II) bisterpyridine systems were used as fluorometric sensors for the detection of the nerve gas G mimics DMMP, DCP and DCNP. Analyte concentrations in the range of 10(-7) to 10(-6) M are detectable in solution. The utilization of a test stripe additionally allows the detection of organophosphonates from the gas phase.

Topics: Chemical Warfare Agents; Coordination Complexes; Fluorometry; Gases; Nitrophenols; Organophosphorus Compounds; Pyridines; Sensitivity and Specificity; Water; Zinc

We developed novel flow-through surface-enhanced Raman scattering (SERS) platforms using gold nanoparticle (Au-NP) immobilized multihole capillaries for rapid and sensitive vapor detection. The multihole capillaries consisting of thousands of micrometer-sized flow-through channels provide many unique characteristics for vapor detection. Most importantly, its three-dimensional SERS-active micro-/nanostructures make available multilayered assembly of Au-NPs, which greatly increase SERS-active surface area within a focal volume of excitation and collection, thus improving the detection sensitivity. In addition, the multihole capillary's inherent longitudinal channels offer rapid and convenient vapor delivery, yet its micrometer-sized holes increase the interaction between vapor molecules and SERS-active substrate. Experimentally, rapid pyridine vapor detection (within 1 s of exposure) and ultrasensitive 4-nitrophenol vapor detection (at a sub-ppb level) were successfully achieved in open air at room temperature. Such an ultrasensitive SERS platform enabled, for the first time, the investigation of both pyridine and 4-nitrophenol vapor adsorption isotherms at very low concentrations. Type I and type V behaviors of the International Union of Pure and Applied Chemistry isotherm were well observed, respectively.

Topics: Gold; Metal Nanoparticles; Nitrophenols; Pyridines; Spectrum Analysis, Raman; Surface Properties; Volatilization

The structures of Ce(4+) complexes that are active for DNA hydrolysis were determined for the first time by X-ray crystallography. The crystals were prepared from a 1:2 mixture of Ce(NH(4))(2)(NO(3))(6) and dipicolinic acid (2,6-pyridinedicarboxylic acid). Depending on the recrystallization conditions, three types of crystals were obtained. Some of the Ce(4+) ions in these complexes have enough coordinated water molecules that can directly and indirectly participate in the catalysis. The distances between the Ce(4+) and the dipicolinate ligand are considerably shorter than those in the corresponding La(3+) and Ce(3+) complexes. On the other hand, the distances between the Ce(4+) and its coordinated water are similar to those for the La(3+) and Ce(3+) complexes. In a proposed mechanism of DNA hydrolysis, the scissile phosphodiester linkage is notably activated by coordination to Ce(4+) and attacked by the Ce(4+)-bound hydroxide. The process is further assisted by acid catalysis of Ce(4+)-bound water.

Topics: Base Sequence; Catalysis; Cerium; Crystallography, X-Ray; DNA; Hydrolysis; Kinetics; Ligands; Nitrophenols; Oligonucleotides; Picolinic Acids; Pyridines; Water

Pyridine has been shown to cause liver and kidney damage in animals and in humans. In a previous study we examined the effects of pyridine on rabbit liver and lung microsomal drug-metabolizing enzymes. In this study, in vivo i.p. administration of pyridine to rabbits caused a significant 3.4-fold increase in kidney N-nitrosodimethylamine (NDMA) N-demethylase activity as compared to the activity in control rabbits. The same treatment also significantly stimulated the activity of other cytochrome P4502E1-associated enzymes. The activities of p-nitrophenol hydroxylase and aniline 4-hydroxylase in kidney microsomes were increased 4.9-and 4.5-fold, respectively. Pyridine treatment increased the P450 content of the kidney 1.6-fold (P<0.05). SDS-PAGE of both kidney and liver microsomes of pyridine-treated rabbits showed a protein band of enhanced intensity at 51,000 Mr migrating in the region of cytochrome P4502E1. p-Aminophenol, a 4-hydroxylation product of aniline, has been shown to be nephrotoxic and NDMA, a procarcinogen, has been shown to be carcinogenic following bioactivation by NDMA N-demethylase in a number of tissues including the kidney. Since pyridine was shown to be nephrotoxic, it is expected that pyridine potentiates the toxic and/or carcinogenic effects of aniline, p-nitrophenol and NDMA through induction of their metabolism by the cytochrome P450-dependent drug-metabolizing enzymes.

Topics: Aniline Compounds; Aniline Hydroxylase; Animals; Cytochrome P-450 CYP2E1; In Vitro Techniques; Kidney; Liver; Male; Microsomes; Nitrophenols; Nitroso Compounds; Oxidoreductases, N-Demethylating; Pyridines; Rabbits; Stimulation, Chemical

Cytochrome P450 2E1 participates in the bioactivation of a wide variety of environmental and occupational pollutants. Such reactions may lead to the production of active carcinogenic metabolites. The presence of P450 2E1 in the testis and prostate has not yet been reported. In the present study, cytochrome P450 2E1 mRNA has been identified in the rat prostate and testis by reverse transcription PCR, southern blotting, and DNA sequencing. P450 2E1 protein from rat testis could be detected with immunoblot analysis, but was not detected in the prostate. The hydroxylation of p-nitrophenol, known to be mediated by P450 2E1, was demonstrated by HPLC measurement of product formation in microsomal fractions from the rat testis, but again not from prostate. Exposure of rats to pyridine resulted in a 2.9-fold increase of p-nitrophenol hydroxylation by testicular microsomes. Diethyldithiocarbamate, a selective mechanism-based inhibitor of P450 2E1, or a P450 2E1 monoclonal antibody, caused marked inhibition of testicular microsomal p-nitrophenol hydroxylase activity. These results indicate that cytochrome P450 2E1 is present in the rat testis, and that it is elevated by the treatment of the animals with pyridine. Thus, the presence and inducibility of cytochrome P450 2E1 in the testis may be of significance in the bioactivation of environmental chemicals to genotoxic metabolites.

Topics: Animals; Cytochrome P-450 CYP2E1; Cytochrome P-450 CYP2E1 Inhibitors; Ditiocarb; Gene Expression Regulation, Enzymologic; Hydroxylation; Male; Microsomes; Nitrophenols; Prostate; Pyridines; Rats; RNA, Messenger; Testis

N-tert-Butoxycarbonylamino acids (Boc-Xaa-OH) were coupled with p-nitrophenol (HONp) in dichloromethane using N,N'-dicyclohexylcarbodiimide (DCC) and N-ethyl-N'(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), and the products were identified and quantitated by high-performance liquid chromatography. Boc-Xaa-OH with Xaa = Val was coupled also with pentafluorophenol (HOPf) and hydroxy-containing additives (HOR), and the products were similarly determined as the methylamides. EDC-mediated reactions of Boc-Xaa-OH gave 8-25% of Boc-Xaa-Xaa-OR as well as Boc-Xaa-OR for R = Ph, Np, Pf, benzotriazole (Bt) and 5-norbornene-endo-2,3-dicarboxamide; DCC-mediated couplings, 5-7% for R = Np and Bt. No dimer was formed in couplings with N-hydroxysuccinimide or 3-hydroxy-4-oxo-3,4-dihydro-1,2,3-benzotriazine. Dimerization was eliminated from DCC-mediated reactions by the addition of 1 equiv. of N-methylmorpholine, from the EDC-mediated reactions by carrying them out in pyridine. Dimerization is attributed to formation of the intermediate 2-alkoxy-5(4H)-oxazolone that undergoes fragmentation to the N-carboxyanhydride, which reacts with the alcohol giving amino acid ester. Ester produces dimer by aminolysis of the O-acylisourea. Decomposition (1.4%) was also detected by analysis for H-Val-Phe-OMe in DCC-mediated reactions of Boc-valine with H-Phe-OMe, and was demonstrated to be caused by the hydrochloride of the ester salt that had been neutralized with N-methylmorpholine. Decomposition was eliminated by the addition of 5% of pyridine, which also had the beneficial effect of suppressing N-acylurea formation.

Topics: Amino Acids; Dicyclohexylcarbodiimide; Esters; Formic Acid Esters; Hydrochloric Acid; Hydroxylamines; Methylene Chloride; Models, Chemical; Nitrophenols; Peptides; Pyridines

Topics: Adenine Nucleotides; Adenosine Diphosphate; Adenosine Triphosphate; Animals; Cattle; Cornea; Electrophoresis; Epithelium; Metabolism; NAD; NADP; Nitrophenols; Nucleotides; Pyridines; Research; Sulfur Isotopes; Thioctic Acid; Tissue Extracts